1. Field of the Invention
The present invention pertains to a termination of a fiber optic cable or waveguide. The invention more particularly concerns a termination that takes the form of a field repairable hermaphroditic connector.
2l . Discussion of the Background
Presently, the control of fast, secured communication translates into power. Thus, secured communication lines are a highly valued commodity. Perhaps no where is the need for secured communications so desired as it is on the battlefield. Communication lines transmit data to coordinate the individual components of a larger unit. Communication lines transmit logistical data. Communication lines transmit data concerning the positions of enemy targets. Communication lines transmit data concerning strategic and tactical placement of ordinance and personnel. A breakdown of communications can result in disaster. Throughout history, effective communications have prevailed as a key element to successful military engagement.
In the past, communications which could not be secured on a single line were broadcast over the airwaves. To prevent others from knowing the contents of the communications, the communications were coded. The intended recipient of the coded message then decoded the communication to reveal the contents of the message. Military history is replete with examples of code breakers successfully uncovering the secrets contained within the coded communication.
Other methods were developed to secure communication lines, such as sending a communication over a dedicated wire cable. Such cables can be tapped or the electrical field can be used to induce an electrical current in another electrical device so that the communication can be monitored.
Another problem with communication lines is that slow or small amounts of transferred data is akin to no communication what-soever. Additionally, modern devices require an ever increasing amount of data so that the devices operate properly. Thus, there is a need for data communication transmission mediums which convey large amounts of information per unit time; i.e., a large bandwidth.
In the modern battlefield, it is envisioned that a command center will link together groups of tanks and artillery batteries with a series of secured communication cables. To overcome the problems described above, manufacturers developed fiber optic cable to convey military communications. The fiber optic cable is a secure, hard-wired, line of communication. A fiber optic cable can not be easily tapped as an electrical wire since optical signals do not induce electromagnetic fields as does an electrical wire conducting electricity. Furthermore, the fiber optic cable has a large bandwidth; that is, it conveys large amounts of information per unit time. The termination device of the fiber optic cable includes a lens forming a so-called expanded beam connector. The advantage of an expanded beam connector is that it is somewhat tolerant of environmental debris contaminating the union between the two termination devices. In practice, the lens expands the beam of light exiting the optic fiber. The other lens in the adjacent termination device takes the expanded beam of light and focuses it back down to a small point and introduces it into the optic fiber of the other cable. When a small amount of debris blocks a portion of the expanded light signal the communication is not corrupted. Thus the expanded beam termination device achieves one of the requirements of a battlefield communication device.
However, expanded beam termination devices have a downside, the insertion loss is relatively high. The insertion loss is high due to expanding the light beam. The expanding light beam is partially scattered and lost, thus, the signal looses power at each union of termination devices. The insertion loss prevents a number of the optical cables from being ganged together since the signal would eventually be lost at the end of the last optical cable; i.e., there would be no usable light energy emanating from the cable. Therefore, the distance between signal transmitting and signal receiving devices is limited unless expensive, cumbersome, power boosting, relay equipment is connected to the optical cable between the transmitting and receiving devices.
Another downside of expanded beam connector termination devices is that once the termination device becomes so fouled with environmental or other debris, it is very difficult, if not impossible, to clean and/or fix the termination device. Thus, the entire length of cable must be replaced, provided a replacement cable is available.
Furthermore, battlefield conditions require that the coupling of two termination devices be simple. Simplicity is an important design characteristic since a soldier may be mating together two termination devices in a dark battlefield. Battlefield conditions also require that the termination devices be structurally robust so as to withstand the repeated impacts imparted by military vehicles, explosive ordinance, and natural environmental calamities. However, even ordinary battlefield rigors and debris may take their toll on one or many termination devices thus necessitating their repair or replacement.
Thus, there is a need for a robust, field repairable termination device which has a low insertion loss when mated with another termination device and which is easily connected to another termination device in the field.